SWI as an Alternative to Contrast-Enhanced Imaging to Detect Acute MS Lesions

Area of Science:

• Neuroimaging
• Radiology
• Neurology

Background:

• Acute inflammatory activity in multiple sclerosis (MS) lesions is typically assessed using contrast-enhanced T1-weighted MRI.
• Gadolinium-based contrast agents are standard for detecting MS lesion activity.
• Alternative methods for assessing MS lesion activity are needed, especially when contrast agents cannot be used.

Purpose of the Study:

• To evaluate if qualitative analysis of non-contrast-enhanced susceptibility-weighted imaging (SWI) of new T2-hyperintense lesions can distinguish acute from chronic MS lesions.
• To determine if SWI can serve as a potential alternative to gadolinium contrast agents for assessing MS lesion activity.

Main Methods:

• Review of serial MRI studies from 55 MS patients, identifying 169 new T2-hyperintense lesions.
• Two neuroradiologists qualitatively assessed SWI signal patterns (hypointense rings, marked/mild hypointensity, iso-/hyperintensity, indeterminate).
• Two other neuroradiologists evaluated postcontrast T1-weighted images for lesion enhancement; Fisher exact test analyzed SWI signal association with enhancement.

Main Results:

• Hypointense rings or marked hypointensity on SWI strongly correlated with absent gadolinium enhancement (93.0% sensitivity, 82.9% specificity).
• Mild hypointensity or iso-/hyperintensity on SWI strongly correlated with present gadolinium enhancement (68.3% sensitivity, 99.2% specificity).
• P-values < .001 indicated strong statistical associations in both cases.

Conclusions:

• Qualitative SWI analysis of new T2-hyperintense MS lesions can predict the likelihood of gadolinium enhancement with high specificity.
• SWI offers a valuable alternative for assessing MS lesion activity in clinical situations where contrast agents are not feasible.
• While SWI has moderate sensitivity, its high specificity makes it a useful adjunct or alternative to contrast-enhanced MRI in MS.